fix z order when replace slot
fix z order when replace slot

dhb118/DragonBonesCPP,DragonBones/DragonBonesCPP,dhb118/DragonBonesCPP,seem-sky/DragonBonesCPP,lite3/DragonBonesCPP,seem-sky/DragonBonesCPP,lite3/DragonBonesCPP,seem-sky/DragonBonesCPP,seem-sky/DragonBonesCPP,lite3/DragonBonesCPP,DragonBones/DragonBonesCPP,lite3/DragonBonesCPP,lite3/DragonBonesCPP,dhb118/DragonBonesCPP,dhb118/DragonBonesCPP,brbranch/DragonBonesCPP,dhb118/DragonBonesCPP,seem-sky/DragonBonesCPP,brbranch/DragonBonesCPP